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https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson
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f3a8f870fa
There are ADC ICs which may have some of the AIN pins usable for other functions. These ICs may have some of the AIN pins wired so that they should not be used for ADC. A common way of marking pins that can be used as ADC inputs is to add corresponding channel@N nodes in the device tree as described in the ADC binding yaml. Add couple of helper functions which can be used to retrieve the channel information from the device node. Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Marcelo Schmitt <marcelo.schmitt1@gmail.com> Link: https://patch.msgid.link/f1d8b3e15237947738912c0d297b3e1e21d8b03e.1742560649.git.mazziesaccount@gmail.com Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
83 lines
2.3 KiB
C
83 lines
2.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Helpers for parsing common ADC information from a firmware node.
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*
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* Copyright (c) 2025 Matti Vaittinen <mazziesaccount@gmail.com>
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*/
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#include <linux/device.h>
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#include <linux/errno.h>
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#include <linux/export.h>
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#include <linux/module.h>
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#include <linux/property.h>
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#include <linux/types.h>
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#include <linux/iio/adc-helpers.h>
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#include <linux/iio/iio.h>
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/**
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* devm_iio_adc_device_alloc_chaninfo_se - allocate and fill iio_chan_spec for ADC
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*
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* Scan the device node for single-ended ADC channel information. Channel ID is
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* expected to be found from the "reg" property. Allocate and populate the
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* iio_chan_spec structure corresponding to channels that are found. The memory
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* for iio_chan_spec structure will be freed upon device detach.
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*
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* @dev: Pointer to the ADC device.
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* @template: Template iio_chan_spec from which the fields of all
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* found and allocated channels are initialized.
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* @max_chan_id: Maximum value of a channel ID. Use negative value if no
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* checking is required.
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* @cs: Location where pointer to allocated iio_chan_spec
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* should be stored.
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*
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* Return: Number of found channels on success. Negative value to indicate
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* failure. Specifically, -ENOENT if no channel nodes were found.
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*/
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int devm_iio_adc_device_alloc_chaninfo_se(struct device *dev,
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const struct iio_chan_spec *template,
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int max_chan_id,
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struct iio_chan_spec **cs)
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{
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struct iio_chan_spec *chan_array, *chan;
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int num_chan, ret;
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num_chan = iio_adc_device_num_channels(dev);
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if (num_chan < 0)
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return num_chan;
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if (!num_chan)
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return -ENOENT;
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chan_array = devm_kcalloc(dev, num_chan, sizeof(*chan_array),
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GFP_KERNEL);
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if (!chan_array)
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return -ENOMEM;
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chan = &chan_array[0];
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device_for_each_named_child_node_scoped(dev, child, "channel") {
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u32 ch;
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ret = fwnode_property_read_u32(child, "reg", &ch);
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if (ret)
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return ret;
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if (max_chan_id >= 0 && ch > max_chan_id)
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return -ERANGE;
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*chan = *template;
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chan->channel = ch;
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chan++;
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}
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*cs = chan_array;
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return num_chan;
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}
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EXPORT_SYMBOL_NS_GPL(devm_iio_adc_device_alloc_chaninfo_se, "IIO_DRIVER");
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Matti Vaittinen <mazziesaccount@gmail.com>");
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MODULE_DESCRIPTION("IIO ADC fwnode parsing helpers");
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